No, there is currently no way to configure default label placement.
There is, however, a partial workaround for this shortcoming:
1. Create an edge.
2. Use F2 to add some meaningless text.
3. Set the desired default label placement.
4. Use the property grid to remove the text.
5. Use the edge context menu to add the edge as template to a user-created palette section (right-click, "Add to Palette").
6. Double-click the new template in the palette to make it the default edge.
Now, edges should have an invisible label with the desired placement. Using F2 to enter text will work on the invisible label. This approach only works for one label, because additional empty labels are hard/impossible to select for editing.
